Armature soldering furnace



Nov. 25, 1952 H. A. ANDERSON 2,619,063

ARMATURE SOLDERING FURNACE Filed NOV. 12, 1949 5 Sheets-Sheet l a W p- INVENTOR.

BY 6-1 Y fl is',

NOV. 25, 1952 H, ANDERSQN 2,619,063

ARMATURE SOLDERING FURNACE Filed Nov. 12, 1949 5 Sheets-Sheet 2 INVENTOR. 86 W NOV. 25, 1952 ANDERSON 2,619,063

ARMATURE SOLDERING FURNACE Filed NOV. 12, 1949 3 Sheets-Sheet 5 Patented Nov. 25, 1952 UNITED ARMATURE SOLDERING FURNACE Hjalmar A. Anderson, Riverside, 111., assignor to Sunbeam Corporation, Chicago, 111., a corporation of Illinois Application November 12, 1949, Serial No. 126,865

3 Claims. 1

This invention relates to soldering furnaces and more particularly to furnaces for soldering armature conductors to their respective commutator bars.

Heretofore the soldering of armature conductors or leads to their respectiv commutator bars has been in general a manual operation, particularly in large size motors. To effect these connections the assemb'lyman individually positions each conductor in proper relation with its respective commutator bar. Where the commutator bars are provided with slotted risers the ends of the conductors are disposed in the slots. When the conductors are in their proper position with respect to the commutator bars the assemblyman heats up the portion of each commutator bar that is to form the connection or joint and the conductor to the proper soldering temperature by a conventional soldering iron. When the parts are at the proper temperature solder is applied in a conventional manner. This method of effecting soldered connections between conductors and commutator bars takes a considerable amount of time and is hazardous to the assemblyman because if he attempts to make a second soldered connection before the first has cooled sufficiently he is apt to be severely burned when he pre-positions a conductor with the adjacent commutator bar. This manual method of effecting connections on armatures is quite costly and is in general an unsatisfactory method of effecting connections.

Accordingly, an object of the invention is to provide a novel furnace construction that is capable of simultaneously effecting a soldered connection between all of the armature conductors and their respective commutator bars.

Another object of the invention is to provide a novel furnace construction for solderin armature conductors to commutators, that is relatively free of hazards to operating personnel, that requires a minimum of manual manipulation in effecting the soldered connections, that greatly reduces the time required to make such connections and that permits of making the connections at a relatively low cost.

Another object of the invention is the provision of a furnace of the above character having novel means for supporting an armature to position the portions of the commutator bars to which the conductors are to be attached so that these portions of the commutator form one wall of a solder distributing chamber capable of retalning solder adjacent these portions at a temperature to effect a soldered connection between the conductors and the commutator bars.

Another object of the invention is the provision of a furnace of the above character, in which a solder distributing chamber for retaining solder is formed by portions of the furnaceand portions of thecommutator bars to which the conductors are to be secured, havin novel means for supplying liquid solder to the chamber at a preselected temperature for a preselected time to effect soldered connections between the commutator bars and conductors.

Another object of the invention is the provision of a furnace of the above character having novel means, for controllin the flow of solder to and from a solder storage chamber and the solder distributing chamber.

Another object of the invention is the provision of a furnace of the above character, in which a solder distributing chamber for retaining solder is formed by portions of the furnace and portions of the commutator bars to which the conductors are to be attached having means for supplying molten solder to the solder distributing chamber having novel means for limiting the level of solder in the solder distributing chamber whereby to effect a good soldered connection between the bars and the conductors while at the same time preventing damage to the insulation on the conductors.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which Figure 1 is a side elevational view of a furnace embodying the present invention with portions cutaway to show a solder displacement plunger in its retracted position;

Fig. 2 is a fragmentary sectional view through one of the cubical portions of the furnace showing the solder displacement plunge in its lower operating position;

Fig. 3 is an enlarged fragmentary vertical sectional view showing details of construction of the support means for the armature;

Fig. 4 is a plan View of the furnace with portions cutaway to show details of construction;

Fig. 5 is a sectional view taken substantially along the line 5-5 in Fig. 4;

Fig. 6 is a wiring diagram of an electrical control circuit for the furnace;

Fig. 7 is a vertical sectional view of a modification of the invention;

Fig. 8 is a sectional view showing a modification of an adapter ring, and

Fig, 9 is an enlarged side elevation view of the electrode holder shown in Fig. 7.

Referring now to the drawings the invention is shown embodied in a furnace for effecting a soldered connection between the conductors or leads I! of an armature l2 and the commutator bars 13 of a commutator Is. For purposes of illustrating the invention each commutator bar 13 comprises a body l6 and a riser I! at one end of the body. The riser IT is formed by spaced side members that define a slot for receiving the conductor I l as best seen in Fig. 3. The commutator bars l3 are assembled as by spaced V rings I8 and IS on a shaft 2! so that the risers define an annular shoulder portion 22 extending outwardly from the periphery of the body portion of the commutator [4. It is to be understood that the furnace disclosed herein may also be used for soldering the conductors to the commutator bars in commutators having other constructions.

While the body of the furnace may assume many different shapes as will be apparent to those skilled in the art, forpurposes of illustration it is shown in Fig. 4 as comprising a cylindrical shaped central portion 24 and a pair of cubical portions 26 on diametrically opposed sides of the central portion. The central portion 2 3 and the cubical portions 26 are mounted on a bottom 21 supported on a base 28. Each of the cubical portions 26 is defined by spaced upstanding members 29 interconnected at opposite ends by spaced members 3| and 35. The central portion includes arcuate-shaped members 32 rigidly secured at opposite ends to the upstanding members 29 as best seen in Fig. 4. With this construction the arcuate members 32, the side members 29 and the bridging members 3! define an outer peripheral wall for the furnace. Disposed between the arcuate members 32 and in concentric relation therewith is an upstanding cylindrical sleeve member 33 defining an inner wall of the furnace, the latter wall being shorter than the outer wall. The u wardly facing opening of the cylindrical member is suific ently large to form a mouth sha ed to receive the commutator end of the armature l2. The tops of the inner and outer walls are interconnected by a member 34 shaped to define with the outer'wall an upstanding portion 36 and with the inner wall an upstanding portion 31, a bridging portion 38 between the upstanding portions 36 and 31 to form with said upstanding portions 36 and 31 a channel or annular recess 39 extendin around the opening of the cylindrical member 33, and a flan e 4| resting on to of the cylindrical member 33 and partially overlying the mouth of the upwardly facing opening therein. The annular channel 39 is shaped to'receive suitable heating elements 42 such as the resistance units shown in Figs. 1 and 3 restingon the brid ing portion 38 and connected to terminals 43 and 44 or ready connection to an external source of power. As

shown the terminals are mounted on a suitable support 45 aflixed to one side of the central portion 24. Rock wool or other suitable insulating material may be disposed between the inner and outer walls as shown in Fi for insulation purposes. Preferably a partition 5!! is disposed between the inner and outer wall ortions at a point spaced upwardly from the bottom 27 to support the rock wool beneath the annular chamber 33. An annular channel shaped member 46 'is attached to the interior of the sleeve member 33 beneath the flange 4| to provide a support therefor and a mounting for an armature support flange 41 extending inwardly of the opening in the cylindrical member 33. Annularly spaced uprights 48 adjacent the inner wall of the body extend between the bottom 2! and the channel member 46 for reinforcement purposes.

In this embodiment of the invention the armature I2 is arranged to be mounted on the flange 4'! in an upright manner as shown in Figs. 1 and 3. For this purpose an adapter plate or ring 49 is provided having an opening 5! of substan tially the same size as the diameter of the commutator l4 and a shoulder portion 52 shaped to abut against the shoulder portion 22 of the commutator. The adapter ring 49 is of a diameter larger than the opening in the flange 4'! so that when the adapter ring 49 is in the position shown in Fig. 3 the adapter ring overlies the flange 4'! to be supported thereby. The flange 41 and adapter ring 49 are preferably dimensioned and shaped so that the risers I! and conductors or leads H are positioned in spaced relation to the upstanding portion 36 and together with it and the upstanding portion 31 define a solder distributing chamber 54 (see Fig. 3) encircling the commutator l4. A gasket 55, in the form of a ring having a circular cross section, is disposed between the flange 41 and a shoulder 56 on the adapter plate 49to prevent leakage of solder from the solder distributing chamber 54.

Disposed in each of the cubical portions 26 is a solder storage pot or well provided with means for transferring the solder from the pot to the distributing chamber 5 so that molten solder may be applied to the connections between the commutator bars [3 and their respective conductors ll. As shown herein each solder pot is in the form of a container 57. At its lower end each container comprises three compartments 58, 59 and Bi as best seen in Fig. 4, and at its upper end each container has a single compartment in alinement with and forming an upper part of the compartment 59. The sides of the container are spaced from the sides of the cubicals and rock wool (see Figure 1) or the like is disposed between the respective walls of the cubical and the container for insulation purposes. Suitable means for heating the solder may be disposed in the outer compartments 58 and Bi. In this instance the heating means comprises a resistance unit 62 having a generally U shape with the bridging portion spanning the lower end of the compartment 59 and its leg portions extending upwardly through the compartments 58 and Si and terminating at terminals 63 and 6t mounted on top of the body on opposite sides of the container 51 to be readily accessible for connection to an external source of power. A charge chute 66 opening on the top of the body is provided for introducing bar solder or the like to the container 5? through an opening 61 formed in the container 5! adjacent its bottom. A pivotally mounted cover 63 normally closes the upper end of the chute 66 as shown in Figure 1. To introduce solder into the chute the cover 68 is moved to the dotted line position shown in Figure 1. A solder displacement plunger H is mounted in the container 5'? for movement between a position in which it is in the upper end of the compartment and a position in which it is disposed in the lower end of the compartment 59. In the latter position the plunger H forces the solder in the container 5? into the solder distributing chamber 55 through an opening F2 formed in the side walls of the container 5?. Vertically extending strips 15 (see Fig. 4) secured to the walls defining the compartment 59 serve to guide the plunger 1| in its up and down movement.

Suitable means is provided for controlling the movement of each plunger H. In this instance each plunger is connected to one end of a piston, not shown, of a fluid operated unit 13 as by a rod '54 extending through an opening in the top of the container 51. Each fluid operated unit 13 is mounted on an upstanding bracket 16 rigidly secured to the top of the body as by welding. Vertically spaced brackets 11 engage opposite ends of each cylinder 18 of each fluid operated unit :to secure the latter on their respective brackets 16 in aconventional manner. The units are positioned to be in overlying relation with their respective containers 5i. The fluid oper ated units 13 are under the control of a suitable control valve unit 79. The latter is connected to the upperend of each cylinder 18 by a conduit 8l, to the lower end or each cylinder s'l8zbya conduit '82 and tea suitable pressure .fiuid source byconduit 83.

The control valve unit it may be manually operated, mechanically operated, electrically operated, or operated by combinations of the afore- -going. Forpurposes'of illustrating the invention the control valve unit 79 is an electrically operatediunit. 'Since many suitable solenoid operated valves are commercially available and their constructions are so well known the details of construction of the control valve unit 779 are not shown herein. For purposes of showing the operation of the furnace however the solenoid coils of the control unit F9 are indicated by the numerals M and 85 in the electric circuit shown in Fig. 6. The control unit i9 is arranged so that when one of the solenoid coils is energized the fluid operated units are connected to the pressure fluid supply so that the solder displacement plungers H are forced downwardly to assume the position shown in Fig. 2. When the othersolenoid coil is energized the fluid operated units '13 are connected to the pressure fluid supply so that the plungers l! are urged to their upper positions to assume the position shown in Figure '1.

In Fig. 6 there is shown one embodiment of an electric control circuit that may be used to control the operation of the furnace. This control circuit is arranged so that by pressing a single push button to initiate operation of the circuit the furnace goes through its complete cycle of operation and returns the moving parts to their initial position at the conclusion of the soldering operation so that the furnace is ready for a subsequent soldering operation.

The control equipment for this circuit includes relays IR, ER and 3B, a timing relay TR, a fused double pole knife switch 89 for connecting the control circuit to a source of power, a switch 9| in the form of a push button, normally closed limit switches 92, one associated with each plunger 7! and arranged to be actuated when the plunger is in its upper position, a transformer 34 and a liquid level control unit The switches 52 in this instance are mounted on the brackets to have their actuating plungers Bdproject downwardly. Since the actuating mechanism is the same for each switch only one will be discussed'in detail. The actuating mechanism includes a slidable pin 56 arranged to engage the plunger 65. As shown the pin til is mounted to project through a passageway formed in a pin guide and support bracket 95 rigidly attached to the bracket 16 in spaced relation to the switch 52. At its extreme lower end the pin fill is formed with an arm its: shaped to engage a collar Hi5 rigidly attached to the rod "it of the fluid operated unit so that when the plunger H is in its upper position the switch 92 is opened.

The control unit '56 comprises a pair of electrodes ST and 93. The electrode 9! is mounted on an arm 99 rigidly attached to the upright it, not shown, so thatthe lower end of the electrode is disposed in the solder distributing chamber 54. The electrode 98 is slidably mounted on an arm Hl'l, rigidly attached (not shown) to the upright 'ldto be disposed in the solder distributing chamber 54 so that the lower end of the electrode 98 may be raised or lowered. A spring N32 is disposed between the arm Hll and the head I03 on the electrode 98. The spring is biased so that it tends to urge the electrode upwardly. Overlying the head IE3 is an eccentric cam I04 rotatably mounted on an arm I06 rigidly attached, not shown, to the bracket 16. The position of the cam HM may be'adjusted by a handle I01. By changing the position of the cam with this construction the lower end of the electrode 98 may be moved up or down. Thus the level of solder in the chamber 5% may be varied to accommodate different sizes of commutators.

Assume that the heating elements 42 and 52 are in operation to maintain the solder in a molten state, the bottom portion of the container 51 is filled with solder, that the armature I2 is in the position shown in Figure l and that the switch 89 is connected to power lines L! and L2 respectively. To start the furnace so that it automatically goes through one soldering cycle the operator presses the push button 9% of the selfreturn type to complete a circuit from the line L! through the contacts of the switch 9! to a coil I23 of the relay lR back to the line L2. In operating, ie relay IR closes its normally open contacts lRl to provide a locking circuit for itself. The latter may be traced from the line Li through the normally closed contacts of the timing relay TB! through the contacts iRl, the coil M8 to the line L2. Thus the relay IR is held operated after the start switch 9| is released by the operator and an operating cycle of the control circuit is initiated. At its normally open contacts ER? the relay IR in operating closes a circuit for energizing the coil 34 of the solenoid valve in the control unit 79. This circuit may be traced from the line L! through the contacts 532 the coil 8 back to the line L2. As a consequence the valve is energized so that pressure fluid is introduced into the upper ends of the cylinders '18 of the pressure fluid units 13 to cause downward movement of the solder displacement plungers H. Solder flows from the containers 5? through the openings l2 into the solder distributing chamber 54. Solder flows into the chamber 54 until the level therein corresponds to the preselected setting of the liquid level control 9'5. The level of solder for each type of armature will vary depending on the length of the commutator bars, the risers, location of the insulation on armature conductors, position at which the soldered connection is to be made with the commutator bar where risers are not employed and the like factors. When the level of solder inthe chamber 55 reaches the preselected level, the solder bridges the electrodes t3? and B8 to close an electric circuit to a coil Hi9 of the relay 3B,. The latter circuit includes the electrode 91, the coil ltd, the secondary winding II I of the transformer 9d and the electrode as. The primary winding iii! of the transformer M is connected in a circuit which includes the line Ll, the primary winding 52, one side of the normally open contacts 3R! and the line L2. In operating the relay 3R closes a circuit through its normally open contacts 335 to energize a coil H3 of the timing relay Upon energization of the coil H3 the relay TR operates to open its normally closed contacts TR! to open a point in the holding circuit of the coil H38 of the relay IR. Upon deenergization of the coil ltd? the contacts IRI open to open another point in the holding circuit advantages.

for the coil I08 and the contacts IRZ open to open the circuit to the coil 89 of the control valve unit I9.

While the solder is maintained at the preselected level in the chamber 54 it flows to the connections between the armature leads and the commutator bars. The solder is maintained at a preselected temperature by the heating elements i2 and 62 to obtain good flow character istics and for a preselected time to effect heating of the soldered parts and thereby insure positive soldered connections. After the selected time interval the relay TR operates to close its normally open contacts TR2. In so doing it closes a circuit to the coil II of the relay 2R which may be traced from the line LI through the normally open contacts TRZ, the coil I It, to the line L2. Upon energization of the coil II 5 the relay 2R operates to close its normally open contacts 2RI and its normally open contacts 2R2. At its contacts ZRI the relay closes an obvious holding circuit for the coil H4. The latter may be traced beginning with the line LI through the limit switches 92, the contacts ZRI, the coil H4, and ending at the line L2. At its contacts 232, the relay 2R in operating closes an obvious circuit to energize the coil 85 of the control unit I9. Energization of the latter directs pressure fluid to the bottom of the cylinders I8 and thereby effects upward movement of the displacement plungers II. Solder from the distributing channel 59 flows back into the solder containers 5?. As soon as the level of the solder gets below the electrode 98 the circuit to the coil I99 of the relay 3B is broken and the coil I99 is de-energized. Upon de-energization of the coi1 I99 the relay 3R operates to open its contacts SRI Upon opening its contacts 3RI the circuit to the coil I I3 of the relay TR is broken and it becomes deenergized. Upon de-energization of the coil H3 the relay TR operates to close its normally closed contacts TRI to close a point in the holding circuit for the coil I08 and to open normally open contacts TRZ to open one energizing circuit of the coil II l of the relay 2R. Upward movement of the plungers I I continues until both limit switches 92 are actuated by their respective actuating mechanisms acting between the collar I55 and the plungers 85. Actuation of both limit switches opens the circuit to the coil IM of the relay 2E and efiects de-energization thereof. Upon deenergization of the coil I It the relay 2R operates to open its normally open contacts ZRI to open a holding circuit for the coil H4 and to open its normally open contacts 2R2 to open a point in the circuit to the coil 85 of the control unit E9 to de-energize the coil 86.

Under these conditions the armature may be removed and replaced by another and the above process of soldering the connections repeated. To accommodate different diameters of commutators the adapter plates for different sized armatures should have openings shaped to. accommodate the size of the armature being soldered. Normally some solder spills or leaks between co. mutator bars or between the gasket 55 and the adapter plate 59 or the armature support flange il. This may be collected in a pull drawer 21 or the like disposed in an opening at the bottom of the body as shown in Figure 1. To guard against splattering of solder on personnel or equipment a cover I22 (see Fig. 4) may be provided on the body to overlie the solder distributing channel 5%.

The aforegoing furnace construction has many The furnace is simple to construct and it insures a uniform and simultaneous soldering of all joints between the commutator bars and the respective armature containers. Too, the soldered connections may be made quickly and there is a minimum of manual manipulation in effecting the soldered connections.

In Fig. '7 there is shown a modified form of the invention in which the overall height of the furnace is less than that of the embodiment shown in Figs. 1-6. In this embodiment of the invention the body I3I of the furnace has the same general configuration as that described for the embodiment shown in Figs. 1-6 and includes a centrally disposed upstanding sleeve I32 open at its upper end and shaped to receive the commutator end of an armature or a similarly shaped workpiece, an annular solder distributing chamber I33 encircling the sleeve, a heating element I34 disposed in the solder distributing chamber, an annular shoulder I35 on the interior of the sleeve for supporting an adapter ring I38 shaped to support the armature in a position such that the portion of the commutator to be connected with the conductors defines a portion of the wall of the solder distributing chamber, a gasket I3! between the support ring I38 and the shoulder I36 and a solder storage container or well I39 on each side of the sleeve I32. Each solder storage chamber I39, only one being shown in this instance, is in communication with the solder distributing chamber I33 through an opening I4I (see dotted lines in Fig. '7) formed in a wall between the well I39 and the annular distributing chamber I33. A plunger I42 is mounted for reciprocation in each well I39 to control the flow of solder from the well I39 to the solder distributing chamber. A deflector I43 causes the solder flowing through the opening I iI to flow uniformly about the solder distributing chamber I33.

In this embodiment of the invention each plunger M2 is caused to move between opposed vertical positions by a pair of pressure fluid operated units it mounted on opposite sides of a body of the furnace and under the control of a conventional control unit I45 mounted onthe body I3I. Each pressure fluid unit includes a cylindrical housing I41, a piston, not shown, reciprocably mounted therein, and a vertical piston rod I98 attached to the piston and movable in response to movement thereof. At their upper ends the rods I48 of each pair of pressure fluid units are pivotally connected to a cross arm I99 overlying each plunger I42. Each cross arm I49 is rigidly attached intermediate its ends to the associated plunger Hi2 by a suitable connection I5I. The pressure fluid units I96 operate ina conventional manner such that when pressure fluid is introduced into the tops of the cylinders I all by the control unit I45, the associatedpistons, and in turn the plunger I42, move downwardly as viewed in Fig. '7 and when pressure fluid is introduced to the bottoms of the cylinders IB'I, assuming the pistons are in their lowermost. position, the associated pistons and the plunger I42 move upwardly. Suitable spaced guide wheels I 52 attached to the cross arm I59 engage vertical rigid rails I53 to guide each plunger in its reciprocable movement. The vertical rails are rigidly attached to the body at their lower ends and are interconnected by a bridging member I51 at their upper ends. As shown, the guide wheels are mounted in a suitable manner on a truck I54 secured to the crosspiece I69.

As shown in Fig. '7 a limit switch I58 is mounted on the underside of the bridging member I51 to be engaged by the crosspiece I49 when the latter is in its upper position. To facilitate the collection of waste solder at the bottom of the sleeve I32 a funnel-shaped member I59 is disposed in the sleeve to have its large opening facing the upper end of the sleeve and its small end overlying a drawer IEI. Any solder spilled or wasted during the soldering process is thus directed into the drawer I6I. The latter may be readily withdrawn from the body of the furnace so that the waste solder can be used over.

Figs. 7 and 9 show an alternate electrode support construction for holding or supporting the electrodes I62. In this instance each electrode is held by a holder comprising a link I63 having a split collar I56 at one end defining a vertical opening for receiving one electrode I52, and a link I64 formed with a collar I60 having an opening for receiving a vertical post I61 which projects outwardly from the mounting pad I68 secured to the body I3l. Any conventional means, such as a set screw I10, may be used to secure the collar ISO to the post I61 at a desired adjusted elevation. Any number of links I55 may be used between the links I63 and I64 to interconnect the latter and to locate the electrodes I62 in a desired horizontal position so that they are disposed in the solder distributing chamber I33. The electrode I62 may be connected with a control unit or circuit, such as described hereinbefore through leads I15 suitably connected to the electrode holders as shown.

Fig. 8 shows a modified construction for an adapter ring I1I for supporting an armature.

In this modification the adapter ring Ill is formed with a shoulder I12 shaped to seat on a gasket I13 supported on a shoulder I'M on the inner sleeve I15 in a manner described hereinbefore adjacent a solder distributing chamber I16. The adapter ring I" is formed with a vertically extending chamber I11 defined by spaced walls I18 and I19. Disposed within the chamber I16 is a heating element IBI. The ends of the heating element I83 (one only being shown) project through the bottom wall I82 of the chamber I11 and are adapted to be connected to an electrical terminal connection I88 connected to a suitable power source I81 through the power leads I84.

While I have shown several embodiments and modifications of my invention, it will be understood that I do not wish to be limited thereto since many modifications may be made and I therefore contemplate by the claims to cover such modifications as fall within the true spirit and scope of my invention.

I claim:

1. In a furnace for soldering the conductors of an armature to their respective commutator bars, the combination of a body having an upwardly facing opening shaped to receive the commutator end of an armature and spaced upstanding portions on its upper edge encircling said opening, the outer of said upstanding portions extending upwardly farther than the inner portion, an annular flange adjacent the inner upstanding portion extending inwardly of said opening, an annular adapter plate overlying said annular flange shaped to be supported by said annular flange and shaped to support an armature in said opening in a position to have the portion of the bars connected to the armature conductors in spaced relation to the outer upstanding portion to define with said upstanding portions a solder distributing chamber encircling the commutator, a ring disposed between the flange and the adapter plate to form a seal at the bottom of the chamber, and means for supplying solder to said chamber at a temperature to simultaneously effect a soldered connection between all the conductors and their respective commutator bars.

2. In a furnace for soldering the conductors of an armature to their respective commutator bars, the combination of a body having an upwardly facing opening shaped to receive the commutator end of an armature and an upstanding portion on its upper edge encircling said opening, means for supporting an armature in said opening in a position to have the portion of the bars to be connected to the armature conductors in spaced relation to the upstanding portion to define therewith a solder distribution chamber encircling the commutator, means for supplying molten solder to said chamber in a fluid state, means associated with said distributing chamber for maintaining the solder in said fluid state, electric control means including at least one electrode extending into said solder distribution chamber for limiting the liquid level of solder in said chamber at a level herein the portions of the conductors to be soldered to the commutator are submerged in solder to simultaneously effect soldering of all armature leads with their respective commutator bars.

3. In a furnace of the solder displacement type for simultaneously soldering a plurality of parts to a workpiece which furnace employs interchangeable adapter rings for supporting various sizes of said workpiece and wherein the solder must flow over the particular adapter ring employed in the furnace at any one time, an adapter ring for supporting a workpiece of relatively small size comprising spaced concentrically arranged inner and outer annular members, said inner member having its upper edge shaped to form a shoulder for supporting the workpiece, means for interconnecting the bottom edges of said inner and outer members to define with said members an upwardly facing open annular chamber, a fiange on said outer member shaped to be supported on the furnace for supporting the adapter ring and workpiece and heating means disposed in said chamber whereby said adapter ring is heated so as not to cool solder flowing over the same.

HJALMAR A. ANDERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 767,465 Wirth Aug. 16, 1904 1,209,116 Castaneda Dec. 19, 1916 1,724,395 Conant Aug. 13, 1929 1,725,960 Jones Aug. 27, 1929 1,947,689 Young Feb. 20, 1934 2,072,864 Bauer Mar. 9, 1937 2,145,956 Stern Feb. 7, 1939 2,264,703 Lenz Dec. 2, 1941 2,267,593 Lof Dec. 23, 1941 2,370,467 Hopkins Feb. 27, 1945 FOREIGN PATENTS Number Country Date 538,904 Germany Dec. 19, 1926 

